1. Field
Apparatuses consistent with the exemplary embodiments relate to dual opposing cantilevers, and more specifically, to dual opposing cantilever pads for a hard disk drive (HDD) suspension flexure tail.
2. Description of the Related Art
Hard disk drives (HDD's) include suspension circuits which support the HDD in, for example, a computer. A suspension circuit includes a suspension flexure which is connected to a flex circuit. The suspension circuit provides an electrical connection between a flex circuit (such an actuator flex circuit) and the read-write head of the computer. The suspension circuit consists of a steel layer and one or more intricately patterned copper foil layers with insulating material (for example, polyimide) which separate the conductive layers (for example, the copper and steel layers) from each other.
An electrical connection between the conductive layers is possible using openings in the insulator. The read-write head (mounted on one end of the suspension circuit) flies above the spinning disk of a hard disk drive. The steel layer of the suspension circuit functions as a spring which allows the read-write head to hover above the spinning disk without crashing while the copper circuitry provides the electrical signal which is required for writing and reading data to and from the disk (i.e. converting electrical current to magnetic field for writing and converting magnetic field to electrical current for reading).
FIGS. 1A and 1B illustrate a hard disk drive. A suspension circuit is inserted in the HDD as shown in the drawings. The mid tail of the suspension circuit is inserted, for example, in a groove. The head area of the flex circuit is shown in FIG. 3A and this would be connected to the tail end of the suspension circuit. FIG. 2 illustrates a bare suspension flexure used in a HDD. Such a suspension flexure is called a bare suspension flexure since it will need to be, for example, bent, folded or assembled to include additional parts. Further, the suspension flexure illustrated in FIG. 2 is flat, however, it can be formed, folded and assembled to additional parts prior to being connected with a flex circuit. FIG. 3A illustrates a suspension flexure which is connected to a flex circuit and FIG. 3B is a more detailed drawing illustrating the flex circuit which is connected to the suspension flexure. The flex circuit can also be called, for example, the mating actuator flex circuit. FIGS. 4A and 4B are drawings illustrating the tail end of a suspension flexure.
As shown in FIGS. 4A and 4B, the tail end of the suspension flexure is made of a layer of steel, then a polyimide layer which is placed over the steel layer, copper pads above the polyimide layer, and then a polyimide cover which is placed on the suspension flexure after the copper. FIG. 4B illustrates the copper which is placed on the suspension flexure in more detail. FIG. 5 illustrates a steel side view of the suspension flexure.
Copper pads are spaced throughout the suspension flexure in order to join the suspension flexure with a flex circuit. The tail pad of the suspension flexure provides the electrical connection between the tail end of the suspension circuit to the head pads of the actuator flex circuit. However, as shown in FIG. 4A, since long, unsupported copper tail pads are used in some suspension flexures, the copper pads may be prone to damage (deformation and/or breakage) during ultrasonic washing, and prone to breakage during manufacturing and handling. Also, some current copper pads designs have a rather large size (i.e. long and wide), and therefore, only a few copper pads can be included in the suspension flexure. Further, this can result in a bulky suspension flexure which requires a lot of space. Suspension circuits with added functionality which will require additional pads, and a new and narrower, yet more robust pad design may be needed.
Also, currently, a different tail design is needed based on the different bonding methods which are used to connect the suspension flexure with the flex circuit. That is, tail pads are designed for a particular bonding method. For example, long, narrow unsupported copper pads are suitable for ultrasonic bonding, whereas copper pads supported with a polyimide base and a small volume of steel can be used for hot bar bonding. However, copper pads which are supported with a polyimide base and a small volume of steel which can be used for hot bar bonding are unsuitable for ultrasonic bonding because the polyimide may absorb the ultrasonic energy required for bonding. Similarly, very wide copper pads with a hole in the center can be used for solder jet bonding, but are unsuitable for hot bar bonding because the hole in the copper may cause the solder to wick and transfer onto the hot bar bonding tool which may then transfer onto undesired areas of other parts that use the same machine.